Problem: Solve for $n$ : $-13 = -11 + n$
Explanation: Add $11$ to both sides: $ \begin{eqnarray} \\ \hphantom{-13 {+ 11}} &\hphantom{=}& \hphantom{n} \\ -13 &=& -11 + n \\ \\ {+11} && {+11} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ -13 {+ 11} &=& n \\ \end{eqnarray} $ Simplify. $ n = -2$